The present invention together with projections to maintain even cut effect to wear, cutting performance and durability but it will provide a rotary blade to improve. A rotary blade 11 is provided with a circular ring plate-shaped base portion 20 is connected to the radially outer periphery 24 of the base portion 20 and a blade portion 31. made of synthetic resin. Blade section 31, the outer periphery 24 and 11 split the first point P 2 points adjacent one of equally divided point 1 and the second point P 2 , the first point P 1 from the specific point T 1 first striatum 37a and the second point P which extends up to 2 from the outside of the outer with composed of a second umbilical member 40a that extends to a certain point T 1 , the angle between the first umbilical member 37a and the second umbilical member 40a is set at an acute angle projections the body 35a is set as a reference, the first point P in one direction along the protrusion 35a on the outer periphery 24 1 and the arc of the 3 between the second point P 2 every equal distance and has a shape formed by projecting a plurality of projections shape obtained by rotating the entire circumference to the virtual plane.BACKGROUND 5【課題】 突起体が摩耗しても切断効果を維持すると共に、切断性能と耐久性が向上する回転刃を提供する。【解決手段】 回転刃11は、円形リング板状のベース部20と、ベース部20の外周24に放射状に接続され、合成樹脂よりなる刃部31とからなる。刃部31は、外周24を11分割した等分点のうち隣接する2点を第1点P1及び第2点P2とし、第1点P1から外方の特定点T1まで延びる第1線条体37aと第2点P2から外方の特定点T1まで延びる第2線条体40aとから構成されると共に、第1線条体37aと第2線条体40aとのなす角度が鋭角に設定された突起体35aを基準とし、突起体35aを外周24に沿って一方向に第1点P1と第2点P2との間の円弧の3等分距離毎に全周回転させて得られる複数の突起体形状を仮想平面に投影してなる形状を有するものである。【選択図】 図5
